DESCRIPTION: The vaginal microbiota play an important protective role in maintaining the health of women. Disruption of the mutualistic relationship that exists between bacterial communities in the vagina and their hosts can lead to bacterial vaginosis (BV), a condition in which lactic acid producing bacteria are supplanted by a diverse array of strictly anaerobic bacteria. BV has been shown to be an independent risk factor for adverse outcomes including preterm delivery and low infant birth weight, acquisition of sexually transmitted infections and HIV, and development of pelvic inflammatory disease. National surveys indicate the prevalence of BV among U.S. women is 29.2%, and yet, despite considerable effort, the etiology of BV remains unknown. Moreover, there are no broadly effective therapies for the treatment of BV, and reoccurrence is common. In the proposed research we will test the overarching hypothesis that vaginal microbial community dynamics and activities are indicators of risk to BV. To do this, we propose to conduct a high resolution prospective study in which samples collected daily from 200 reproductive-age women over two menstrual cycles are used to capture molecular events that take place before, during, and after the spontaneous remission of BV episodes. We will use modern genomic technologies to obtain the data needed to correlate shifts in vaginal microbial community composition and function, metabolomes, and epidemiological and behavioral metadata with the occurrence of BV to better define the syndrome itself and identify patterns that are predictive of BV. The five specific aims of the research are: (1) Evaluate the association between the dynamics of vaginal microbial communities and risk to BV by characterizing the community composition of vaginal specimens archived from a vaginal douching cessation study in which 39 women self-collected vaginal swabs twice-weekly for 16 weeks;(2) Enroll 200 women in a prospective study in which self-collected vaginal swab samples and secretions are collected daily along with data on the occurrence of BV, vaginal pH, and information on time varying habits and practices;(3) Determine the gene content (metagenome) of vaginal microbial communities to assess the metabolic potential of representative vaginal communities in women before, during, and after the spontaneous remission of BV;(4) Characterize suites of expressed genes (metatranscriptome) in communities representative of vaginal community types in healthy women, as well as before, during, and after the spontaneous remission of BV;and (5) Apply model-based statistical clustering and classification approaches to associate the microbial community composition and function, with metadata and clinical diagnoses of BV. The large body of information generated will facilitate understanding of vaginal microbial community dynamics, the etiology of BV, and drive the development of better diagnostic tools for BV. Furthermore, the information will enable a more personalized and effective treatment of BV and ultimately, prevent adverse sequelae associated with this highly prevalent disruption of the vaginal microbiome. PUBLIC HEALTH RELEVANCE: Bacterial vaginosis (BV) is the most common vaginal disease in women, and yet its cause and effective treatment remain unknown. BV is associated with many adverse health outcomes, such as preterm delivery of low birth weight babies and increased risk for infection by HIV. This research will contribute valuable information on the causes of BV, help develop improved methods for preventing and treating BV, and may help reduce major reproductive health problems associated with BV.